The invention generally relates to an air bag module and an associated steering wheel, which features a method providing a continuous electrical connection to the vehicle without the use of a contact coil.
A typical driver side air bag module comprises a housing, an inflator, a cushion and a cover. The housing is mounted at or near the steering wheel armature. The inflator and air bag are located within the housing and the cover (and housing) protects the air bag. When the airbag sensor senses a collision has occurred, an electrical signal is sent through a wiring harness, into a contact coil (also known in the art as xe2x80x9cclockspringxe2x80x9d), and into the inflator. A contact coil is used to provide a secure, reliable connection regardless of the orientation of the steering wheel. Upon receipt of this signal, the inflator begins to generate gas, which in turn inflates the cushion. As the cushion inflates, the cover is separated permitting the inflating cushion to expand toward the occupant.
If the inflator could remain fixed on (or become part of) the steering column, and the remaining airbag module components were allowed to rotate about it, the contact coil would be unnecessary. A method of doing this that is known in the art was described in U.S. Pat. No. 5,954,359. In this patent, Ross teaches that it is possible to place a tubular inflator within the steering shaft, and then vent the gas within this shaft and into-the airbag cushion. This is a valid solution; however, it requires not only a tubular style inflator but also a special, non-standard steering shaft.
In accordance with the present invention, a steering wheel assembly contains an inflator subassembly comprising a largely circular inflator of the type typically used in driver side airbag modules; the inflator subassembly also contains a flange that has been welded to the inflator before a gas deflector has been attached to the flange. The steering wheel assembly further contains a steering wheel armature containing a circular orifice for receiving gas from the flange and gas deflector; the steering wheel armature further containing features for attachment of the retaining ring to the steering wheel, and for the attachment of the steering wheel armature to the steering shaft. The steering wheel assembly further contains a; cushion subassembly comprising a cushion surrounding the retaining ring, and a cover surrounding the cushion. The steering.wheel assembly further contains a slip ring that serves to pass electrical signals into the steering wheel assembly for electronics such as the horn, cruise control, radio buttons, etc. As will be seen, the inflator, flange, and gas deflector are fixed to the steering column through the use of a bracket, while the steering wheel armature and the cushion subassembly are allowed to rotate about it, and with the aid of a slip ring, electrical signals can be sent-to the steering wheel for devices other then the inflator. As the inflator generates gas, the gas fills the flange and is forced by the gas deflector to flow through the steering wheel armature and into the cushion. The.cushion then expands, opening the cover, and allowing for restraint of the occupant during a collision.